1. Field of the Invention
The present disclosure relates to the tracking of rolling stock, including railcars and locomotives, and more particularly to the tracking of rolling stock within a controlled area of a railway system, wherein a passage of an axle or wheel is determined within the controlled area and the passage is associated with a corresponding piece of rolling stock within the controlled area, thus locating the rolling stock within the controlled area.
2. Description of the Related Art
A railroad system often includes at least one switchyard in which rolling stock, such as railcars, are routed from tracks leading from a departure point to tracks going to a destination point. A typical switchyard has four main components, namely receiving tracks, a railcar switching operation, a set of classification tracks and a set of departure tracks. Incoming trains deliver the railcars to the receiving tracks. The railcars are processed by the switching operation that routes individual railcars to respective classification tracks. From the classification tracks, the railcars are selectively assembled into trains on the departure tracks.
Two types of switching operations are typically used. The first one is a hump switching. Switch yards that use hump switching are referred to as hump yards. Hump switching uses a hump over which a railcar is pushed by a locomotive. At the top of the hump, the railcar is allowed to roll on the other side of the hump under the effect of gravity. Retarders keep the railcar from reaching excessive speeds. The hump tracks on which the railcar rolls down the hump connect with the classification tracks. One or more track switches establish a temporary connection between the hump tracks and a selected one of the classification tracks such that the railcar can roll in the classification tracks. A departure train is constituted when the requisite number of railcars has been placed in a set of classification tracks. When the departure train leaves the switchyard, the set of classification tracks become available for building a new departure train.
The second type of switching operation is flat switching. The principle is generally the same as a hump yard except that instead of using gravity to direct railcars to selected classification tracks, a locomotive is used to move the railcar from the receiving tracks to the selected set of classification tracks.
However, as switch yards can include tens or hundreds of receiving, classification and departure tracks wherein hundreds or thousands of railcars may pass through each day, the tracking of the railcars represents a significant task, aside from the physical disposition of the railcars themselves.
In addition, railcars carrying intermodal containers can enter the switch yard in the form of a train. Once the train enters the switch yard, the railcars are separated and routed to different storage, maintenance and/or processing tracks. Once a railcar is placed on a processing track, the containers need to be unloaded from the railcar.
A container management system such as provided by APS Technology Group is known. There are two major functions provided by the container management system. The first function provided by the APS system is to capture information about a train entering (or leaving) the switch yard at specific “portal” locations. The second function is to provide location information to the crane system for the purpose of “identifying” specific containers to be unloaded.
However, due to numerous tracks and combinations of switching moves between tracks within the switch yard, the ordering, orientation and locations of individual railcars becomes non-deterministic from the original train information captured by the APS system at the entrance portals. In order to facilitate remote control and automation of the container unloading, a method to track the location of the railcars that are carrying the containers is required.
Therefore, the need exists for a system of tracking the location of rolling stock, such as railcars, within a controlled area of a railway system. The need also exists for a system of tracking within a controlled area, wherein the resolution of the rolling stock location can be tailored to the particular controlled area.
The need also exists for rolling stock tracking capability that can provide the location of all the rolling stock, as to a specific track and ordering and orientation of the rolling stock on the specific track rather than an exact distance to a reference point within the controlled area. Further, it would be advantageous for the rolling stock location to be employed for any of a variety of purposes such as to a secondary operating system, such as the container management system.